* upstream merge

* Fixed bad merge

* More bad merges

* Mostly done, however a few properties missing and tests remain.

* async icons loading

* Left button

* Whoops!

* Added button size

* updated docs

* refactor

* Rebase fixes

* Rebase fixes

* rebase fix

* Rebase fixes

* rebase fixes

* reset contributing

* minor refactor - moved some logic from view o controller

* readme

* doc

* topbar fix

* rm doc

* options presenter fix

* rm userless stuff

* added backgroundImages options

* update readme

* backgroundImage fix

* added unit test

* async await for push and showModal

* async await for push and showModal

* refactored custom transitions

* refactored custom animations

* drawUnder for topBar and bottomTabs

* test fix

Slightly changes topTabs node declaration and removed the container from it.

* Further work on TopTabs and some refactoring

* OptionsPresenter receives views as params
* Remove TopBar and style logic from ViewControllers, these are the OptionsPresenters concern
* StackAnimator isn't coupled to LinearLayout
* Convert Runnable to lambda
* ContainerLayout now implements ReactContainer interface
* Enable desugaring in playground app

* TopTabs unit tests